The effect of heat conduction on 2.5D magnetic reconnection, similar to that in Kopp-Pneuman model, is numerically studied. It is shown that the heat conduction accelerates the reconnection, increases the amount of shrinkage of the closed field lines, and increases the average rise speed of the SXR loop. MHD slow shocks contribute to the SXR loop heating. When the timescale of heat conduction is shorter than the Alfv

A class of pseudo-reconnection caused by a shifted mesh in MHD simulations is reported. In term of this mesh system, some non-physical results may be obtained in certain circumstances, e.g., magnetic reconnection occurs without resistivity. After comparison, another kind of mesh system is strongly recommended.

We performed 2.5-dimensional numerical simulations of magnetic reconnection for several models, some with the reconnection point at a high altitude (the X-type point in magnetic reconnection), and one with the reconnection point at a low altitude. In the high-altitude cases, the bright loop appears to rise for a long time, with its two footpoints separating and the field lines below the bright loop shrinking, which are all typical features of two-ribbon flares. The rise speed of the loop and the separation speed of its footpoints depend strongly on the magnetic field B0, to a medium extent on the density P0, and weakly on the temperature To, the resistivity η, and the length scale L0, by which the size of current sheet and the height of the X-point are both scaled. The strong B0 dependence means that the Lorentz force is the dominant factor; the inertia of the plasma may account for the moderate P0 dependence; and the weak η dependence may imply that "fast reconnection" occurs; the weak L0 dependence implies that the flaring loop motion has geometrical self-similarity. In the low-altitude case, the bright loops cease rising only a short time after the impulsive phase of the reconnection and then become rather stable, which shows a distinct similarity to the compact flares. The results imply that the two types of solar flares, i.e., the two-ribbon flares and the compact ones, might be unified into the same magnetic reconnection model, where the height of the reconnection point leads to the bifurcation.

We present a theoretical model for the shock formation that is related to coronal and interplanetary type II radio bursts associated with coronal mass ejections on the basis of the magnetic reconnection model of eruptive solar flares. Coronal type II bursts are usually observed in the metric wavelength range (metric type II bursts), and interplanetary bursts are usually observed in the decametric-hectometric wavelength range (decametrichectometric bursts). Our research shows that the decametric-hectometric type II radio bursts are produced by the piston-driven fast-mode MHD shock that is formed in front of an eruptive plasmoid (a magnetic island in the two-dimensional sense or a magnetic flux rope in the three-dimensional sense), while the metric radio bursts are produced by the reverse fast-mode MHD shock that is formed through the collision of a strong reconnection jet with the bottom of the plasmoid. This reverse shock apparently moves upward as long as the reconnection jet is sufficiently strong and dies away when the energy release of the reconnection stops or weakens significantly. On the other hand, the piston-driven fast shock continues to exist when the plasmoid moves upward. Our model succeeds in explaining the observational result that the piston-driven fast shock that produces decametrichectometric type II bursts moves faster and survives longer than the other shock.

This paper reviews our recent progress in the numerical study of coronal mass ejections (CMEs) based on flux rope model, which shows that when the reconnection-favored emerging flux appears either within or ABSTRACT on the outer edge of the filament channel, the flux rope would lose its equilibrium, and be ejected, while a current sheet is formed below the flux rope. For the case with emergence within the filament channel, even small flux is enough to trigger the loss of equilibrium, however, there is a threshold for the emerging flux on the outer edge of the filament channel. Given that anomalous resistivity sets in (e.g. when the current density exceeds a critical value), fast reconnection is resulted in, leading to fast eruption of the flux rope and localized flare (either impulsive-type or LDE-type depending on the height of the reconnection point) near the solar surface. The numerical results can well explain why CMEs are not centered on flares and provide hints for CME-flare spatial and emporal relationships.